1. Field of the Invention
The present invention relates to a bit pattern conversion apparatus for dot image data and, more particularly, to a conversion apparatus for converting an input bit pattern into an output bit pattern compatible with a printer or a CRT display unit.
2. Description of the Prior Art
Terminals connected to computers process dot image data in a vertical or horizontal direction. For example, among dot printers, a line printer processes dot image data in the horizontal direction while a serial printer processes dot image data in the vertical direction. For this reason, output to be supplied to a hammer of a printer must be horizontal data in the case of a line printer and vertical data in the case of a serial printer. When data supplied from a host computer is data compatible with a line printer but a printer to be used is a serial printer (or vice versa), the data output sequence must be changed for compatibility with an available printer. This also applies to a character generator or a CRT display unit. When a character generator outputs vertical data and the data must be outputted by a CRT display unit or a line printer capable of processing horizontal data, the vertical data must be converted into horizontal data.
When input data sent from a most significant bit (to be referred to as an MSB hereinafter) is to be processed by a terminal such as a printer and if the printer is to read and process such input data from a least significant bit (to be referred to as an LSB hereinafter) (or vice versa), MSB/LSB conversion must be performed.
When a printing output is to be double expanded or 8-bit input image data is to be processed in 6-bit blocks, an input bit pattern must be converted into a pattern which can be processed by a terminal.
Such vertical/horizontal conversion, MSB/LSB conversion, expansion (doubling), and bit pattern conversion from an 8-bit pattern into a 6-bit pattern are conventionally performed by a program. However, such conversion is time-consuming and delays printing or display.